The properties of intracellular b-glucosidases produced from two yeast isolates identified as Hanseniaspora sp. BC9 and Pichia anomala MDD24 were characterized. b-Glucosidase from Hanseniaspora sp. BC9 was not inhibited by both 20% w/v fructose and 20% w/v sucrose and was slightly inhibited by glucose ([ 40% relative b-glucosidase activity with 10% w/v glucose). b-Glucosidase from P. anomala MDD24 was inhibited by glucose, fructose and sucrose. In the presence of 4-12% v/v ethanol, b-glucosidase from P. anomala MDD24 was stimulated in range 110-130% relative activity whereas b-glucosidase from Hanseniaspora sp. BC9 was substantially inhibited in the presence of ethanol. Finally, juice and wine of the Muscat-type grape variety, Traminette, were selected to determine sugar-bound volatile aroma release, particularly terpenes, by the activity of those b-glucosidases. The results showed that high concentration of free aroma compounds were detected from Traminette juice treated with b-glucosidase from Hanseniaspora sp. BC9and Traminette wine treated with b-glucosidase from P. anomala MDD24. The preliminary results with proposed an application of these enzymes in commercial wine production lead to more efficient of b-glucosidase from Hanseniaspora sp. BC9 in releasing desirable aromas during an early stage of alcoholic fermentation while b-glucosidase from P. anomala MDD24 is suitable at the final stage of alcoholic fermentation.

-The production and characterisation of β-glucosidase from an isolated yeast strain classified as a Pichia anomala MDD24 were studied. The result shows that cellobiose is a good inducer for extracellular β-glucosidase production and optimum concentration is 1.5 percent cellobiose in yeast peptone dextrose medium. The purified β-glucosidase from Pichia anomala MDD24 exhibited a specific activity of 614 ± 14 U mg -1 of protein and a molecular mass of 42 kDa. This enzyme was slightly inhibited by fructose and sucrose in the range of 4 to 20% (w/v). An ethanol concentration between 4 and 20% (v/v) activated β-glucosidase activity, at presence 16% (v/v) ethanol, β-glucosidases obtained maximum relative activity around 150%. The optimum pH and optimum temperature for β-glucosidase activity were 4.5 and 40 °C, respectively. Although the activity under the pH and temperature of wine production (pH 3.5-4.0 and 15-20 °C) was quite low, the enzyme was stable and the relative activities were higher than commercial enzyme under those conditions. The extracellular β-glucosidase from Pichia anomala MDD24 makes it possible to release glucosidically-bound monoterpenes, which are the major contributors to floral and fruity aromas in wines from Muscat-type varieties, at final stage of alcoholic fermentation.

No abstract

A new yeast species (KKU-FW10) belonging to the Candida genus was isolated from Jasminum adenophyllum in the Plant Genetic Conservation Project under The Royal Initiative of Her Royal Highness Princess Maha Chakri Sirindhorn area, Chulabhorn Dam, Konsan district within Chaiyaphum province in Thailand. The strain was identified via analysis of nucleotide sequences from the D1/D2 domain of 26S ribosomal DNA and based on its morphological, physiological and biochemical characteristics. The sequence obtained from yeast isolate KKU-FW10 was 97 percent identical to that of Candida chanthaburiensis (GenBank accession number AB500861.1), with 506/517 (nucleotides identity/total nucleotides) matching nucleotides, nine substitutions and two gaps being detected. This species belonged to the Candida clade. Regarding morphological characteristics, isolate KKU-FW10 presents cream-colored butyrous colonies, vegetative reproduction through budding and, round cells without filaments or ascospores. The major ubiquinone detected was Q-9. The above results suggest that isolate KKU-FW10 is a new member of the genus Candida, and the name Candida konsanensis is proposed for this yeast. The type strain of the new species is KKU-FW10(T) (= BCC 52588(T), = NBRC 109082(T), = CBS 12666(T)). In addition, this KKU-FW10 could potentially produce 58.24 Units/ml of carboxymethyl cellulase when it was cultured in YP broth containing 1.0 % carboxymethyl cellulose for 24 h.

No abstract